Mosaic plate



July 4, 1939. U I 2,164,961

MOSAIC PLATE Filed May 18, 1937 M1 Q G $2391 Patented July 4, 1939 UNITED STATES PATENT OFFICE MOSAIC PLATE -Heinrich Striibig, Teltow, near Berlin, Gartenstadt, Seehof, Germany, assignor to the firm Fernseh Aktien-Gesellschaft; Zehlendorf, near Berlin, Germany Application May 18, 1937, Serial No. 143,396 In Germany June 17, 1936 5 Claims.

sides of the carrier plate. Besides the plate must be provided with a continuous conductive counter electrode for all mosaic electrodes.

The production of such a mosaic plate caused a considerable difiiculties in the past because the mosaic electrodes permeating the plate transversely were usually separatey placed into the plate. For higher definition as required in the development of television, the cost of labor for n making a mosaic plate in such a manner would be prohibitively high. It is the object of the invention to provide means to produce such a mosaic plate for as high a definition as may be required in a simple manner. Thereby, the cost 0 of labor does not depend upon the number of mosaic elements because these are no longer made separately but simultaneously.

According to the invention the mosaic electrodes are made as unsuspended layers which cover the holes in an isolating plate. Whereas the individual electrodes of the mosaic plates so far known have their greatest dimension vertical to the plate, the electrodes in this case will usually consist of thin layers of only small mechanical rigidity which are parallel to the plate and attached to the latter. A mica or glass foil is preferably used for the insulating plate, which may be provided with a metallic layer if necessary, for instance, by evaporation. The unsuspended layers offer the, great advantage that they may be 40 produced simultaneously, for instance, by evaporation.

The necessary holes in the plate may be made, for instance, in a punch press. Preferably the holes are not made individually but also simultaneously. This may be done by etching whereby the parts to remain are screened oif. An advantageous method consists in the use of a stream of compressed air into which, for instance, carbor rundum powder is mixed. A network is arranged between the blast and the plate. The particles of the carborundum powder may then only reach the plate through the holes in the network. They are directed with such a velocity upon the plate that the latter is punctured. It has been found that very regular holes in a mica plate may be obtained in this manner without destroying the remaining material. It may be understood that any other pattern may be used instead of the network which is provided with the required holes and covers the parts of the plate which are not to be punctured.

Before depositing the mosaic electrodes by evaporation, it is advisable to provide the side of the insulating plate remote from the source of radiation with a removable auxiliary layer, for instance, a collodium solution. After removal of this auxiliary layer the mosaic electrode has a conducting surface on both sides of the plate.

The invention may further be explained with the aid of the drawing which shows a cross section of a very small section of the mosaic plate according to the invention.

Figs. 1 and 2 show two stages in the production, whereas Fig. 3 shows the finished plate.

I indicates the base plate, which may consist of a mica foil. 2 indicates the neighboring wires of a network. First a continuous metallic layer 3 is produced upon the plate, by evaporation from above (Fig. 1). Then the plate is punctured from below through the network 2so that the holes are made at the spots 4. It has been found that the holes produced in this manner ,are considerably smaller than the openings in the network. After the puncturing processes the continuous metallic ayer 3 no longer reaches to the edge of the hole but ends in a certain distance from the edge. Often a ridge is produced when puncturing the plate which prevents the metallic layer reaching the edge of the hole.

A thin collodium layer 6 is now spread over the metal-covered side, which collodium layer also covers the holes. Then a metal is distilled from below and. again through a network or any other suitable pattern. It is best to distill the metal through the same network which was used when puncturing the plate, so that this network may be attached to the plate during the entire process of production and may be removed only during the spreading of the collodium layer if necessary. The distillation produces a number of mosaic elements 5 which cover the holes and are isolated against the metallic layer 3 (Fig. 2).

If the collodium layer is now removed, for instance, by dissolving in acetone, and the network is also removed, a finished mosaic plate is obtained which fulfills all requirements (Fig. 3). The application of mica has the further advantage that no later liberation of gas when operating the tube is to be feared. A mosaic applicable in a one-sided Iconoscope. In this case the auxiliarylayer 8 mayremain upon the plate. In order topress the network against the plate during the process of production it is preferred to use a holding device. The simplest way is to press the mica plate and the network against a plane which is provided with a slight curvature. In the drawing such a plane would be pressed on from below. The counter electrode required for the application of a mosaic plate in picture analyzing tubes must not necessarily be a continuous metallic layer on or also inside of an isolating plate. 'The network used for the production may be attached to the other 'side of the plate after it has fulfilled its pre,

vious purposes. In this case a special continuous metallic layer is not necessary as the network serves as counter electrode for all mosaic electrodes. When using the plate as a photomosaic for picturev analyzing tubes one surface of the mosaic electrodes is activated with a strongly photosensitlvematerial, preferably caeslum, while the-other surface scanned by the cathode ray beam is preferably made of another metal, which itself, or its oxide, does not bind caesium. Nickel. is especially suitable for this purpose. 'In the distillation two layers directly upon each other are produced, which layers may consist, for instance, of silver and nickeL- The surface of the silver layer is then oxidized and activated with caesium.

I claim: I

1. The method of forming a photo-sensitive mosaic plate which comprises distilling a continuous conductive coating upon one side of a thin insulating plate, placing an apertured network against'the opposite side of said insulating plate, directing, a stream of compressed air carrying carborundum powder against said plate through said network until a minute hole is produced in registry with each apertured portion of said network, placing a continuous coating of collodion over said conducting layer and holes, distilling nickel through said network into said insulating plate apertures and .against said collodion layer, distilling silver through said network on to said nickel, dissolving saidcollodion layer, treating said silver portions with caesium and removing said network.

2. A photo-sensitive mosaic plate comprising a perforated sheet of insulating material, a layer of conductive material on one face' of said perforated sheet of insulating material and perforated in'alinement with the perforations through said sheet of insulating material, a plurality of isolated conductive elements on the opposite face of said sheet of insulating material, each extendinginto one of said perforations through said sheet of insulating material but terminating in spaced relationship to said layer of conductive material.

3. The steps in the method of preparing a photo-sensitive mosaic plate which comprise coating a sheet of insulating material with a layer of conductive material, simultaneously perforating said sheet of insulating material and conductive coating, temporarily covering the edges of said conductive coating bordering on said perforations, filling said perforations through said sheet of insulating material with conductive material and subsequentlyuncovering the covered edges of said conductive coating.

4. A photo-sensitive mosaic plate comprising a perforated sheet 'of insulating material, a layer of conductive material on one face of said perforated sheet of insulating material and perforated through said sheet of insulating material, a plurality'of isolated conductive elements on the opposite face of said sheet of insulating material, each extending into one of the perforations in said sheet of insulating material but terminating short of complete passage therethrough.

5. The steps in the method of preparing a photo-sensitive mosaic plate which comprise coating a sheet of insulating material on'one side with a layer of conductive material, placing a fine-mesh screen against the opposite side v f of said insulating sheet and bombarding said insulating sheet with a hard powdered material at a velocity sufiicient to simultaneously perforate both said sheet of insulating material and said conductive coating, temporarily insulating subsequently removing said screen HEINRICH sraiinra.

inalinement with said perforations. 

